tests: spi_loopback: Fix fail handle of thread test

Right now the thread test case does not handle when the test fails, the
test will be aborted by ztest in one of the spawned threads, and cause
desynchronization which messes up the rest of the test. Fix by
synchronizing in the case of fails and return fail from main test thread
instead of the spawned ones.

Signed-off-by: Declan Snyder <declan.snyder@nxp.com>

Author: decsny

tests/drivers/spi/spi_loopback/src/spi.c

@@ -700,16 +700,17 @@ static K_SEM_DEFINE(sync_sem, 0, 1);
 static uint8_t __aligned(32) tx_buffer[3][32];
 static uint8_t __aligned(32) rx_buffer[3][32];
 
+atomic_t thread_test_fails;
+
 static void spi_transfer_thread(void *p1, void *p2, void *p3)
 {
 	struct spi_dt_spec *spec = (struct spi_dt_spec *)p1;
 	uint8_t *tx_buf_ptr = (uint8_t *)p2;
 	uint8_t *rx_buf_ptr = (uint8_t *)p3;
+	int ret = 0;
 
 	/* Wait for all threads to be ready */
 	k_sem_give(&thread_sem);
-	k_sem_take(&sync_sem, K_FOREVER);
-
 	/* Perform SPI transfer */
 	const struct spi_buf_set tx_bufs = {
 		.buffers = &(struct spi_buf) {
@@ -726,11 +727,19 @@ static void spi_transfer_thread(void *p1, void *p2, void *p3)
 		.count = 1,
 	};
 
-	zassert_equal(spi_transceive_dt(spec, &tx_bufs, &rx_bufs), 0,
-		      "SPI concurrent transfer failed");
+	k_sem_take(&sync_sem, K_FOREVER);
+
+	ret = spi_transceive_dt(spec, &tx_bufs, &rx_bufs);
+	if (ret) {
+		TC_PRINT("SPI concurrent transfer failed, spec %p\n", spec);
+		atomic_inc(&thread_test_fails);
+	}
 
-	zassert_mem_equal(tx_buf_ptr, rx_buf_ptr, 32,
-			 "SPI concurrent transfer data mismatch");
+	ret = memcmp(tx_buf_ptr, rx_buf_ptr, 32);
+	if (ret) {
+		TC_PRINT("SPI concurrent transfer data mismatch, spec %p\n", spec);
+		atomic_inc(&thread_test_fails);
+	}
 }
 
 /* Test case for concurrent SPI transfers */
@@ -752,6 +761,8 @@ static void test_spi_concurrent_transfer_helper(struct spi_dt_spec **specs)
 		k_sem_take(&thread_sem, K_FOREVER);
 	}
 
+	atomic_set(&thread_test_fails, 0);
+
 	/* Start all threads simultaneously */
 	for (int i = 0; i < 3; i++) {
 		k_sem_give(&sync_sem);
@@ -761,6 +772,8 @@ static void test_spi_concurrent_transfer_helper(struct spi_dt_spec **specs)
 	for (int i = 0; i < 3; i++) {
 		k_thread_join(&thread[i], K_FOREVER);
 	}
+
+	zassert_equal(atomic_get(&thread_test_fails), 0);
 }
 
 /* test for multiple threads accessing the driver / bus with the same spi_config */